The present invention generally relates to a magnetic tape and more particularly, to a tape cassette for storing therein a magnetic tape capable of recording and reproducing audio and/or video information such as music, video images, etc.
Conventionally, as a tape cassette, there has been proposed a compact cassette, for example, as shown in FIG. 5, which is so arranged that a magnetic tape accommodated therein is exposed from a cassette shell housing 38, or cassette shells (referred to as a cassette shell housing hereinafter) through a magnetic head insertion window 34 and pinch roller insertion windows 35 formed at one side of the cassette shell housing 38 for inserting the magnetic heads and pinch rollers thereinto as disclosed, for example, in British Patent Publication No. 1,052,249 (the compact tape cassette in FIG. 5 will be described in more detail later).
Meanwhile, another conventional compact cassette 41 as shown in FIG. 16 includes a shield board 47 provided in front of magnetic heads 21 inserted in the insertion windows of the cassette shell housing 48. This shield board 47 protects the magnetic heads against electromagnetic waves emitted from mechanisms and external units.
Similarly, there is also available a tape cassette having a shutter member which shuts off the magnetic head insertion windows and pinch roller insertion window, etc. when the tape cassette is in a non-use state. These are called, for example, video tape cassettes or digital audio tape cassettes (referred as "DAT" hereinafter), each of which tape cassettes is arranged to pull out the magnetic tape when mounted on a magnetic tape recording/reproducing apparatus through rotation of the shutter member which closes such windows.
In the conventional compact cassette as referred to above, however, since the magnetic tape is exposed by the insertion windows for inserting the magnetic heads in the cassette shell housing and the insertion window for inserting the pinch-roller in the cassette shell housing, etc., dust entering through such insertion windows tends to adhere to the recording and reproducing surface of the magnetic tape. Also, an operator's hand may unintentionally or accidentally touch the recording and reproducing surface, thereby damaging it.
Meanwhile, in the video tape cassettes and DAT cassettes or the like as referred to above, it is not possible for dust or the like to enter inside, since the magnetic tape is protected by the shutter member when it is closed. But in the case where the tape cassette is to be mounted on a magnetic recording/reproducing apparatus for recording and reproducing, it is necessary to open the shutter member so as to pull out the magnetic tape, such that dust or the like may adhere to the recording and reproducing surface of the magnetic tape which is then exposed.
Moreover, during the process for rotating the shutter member and when the shutter member is in an open position, the tape cassette undesirably occupies a larger volume, thus presenting a problem which hinders reduction in size of related appliances.
Another disadvantage is that in the shielding structure of the above conventional compact cassette, there is provided no means for shielding against the electromagnetic waves from the upper, lower, left, and right sides of the magnetic heads. In order to reduce the influence of the electromagnetic waves from the mechanisms as such as possible, another means to prevent electromagnetic waves inside the mechanism must be introduced.